Vehicle seats often include a mechanism that allows them to move back and forth, for example to adjust leg room or to facilitate reclining the seat. In the event of an accident, the forces acting on the seat, with or without a passenger, can cause unwanted and dangerous movement of the seat via the mechanism.
In a typical reclinable aircraft seat, the recline apparatus, which enables the movement of the seat from upright through recline to a bed position, comprises a movable upper carriage coupled to a fixed lower structure that is connected to the aircraft floor structure. At any position within its full range of movement the upper carriage may be stopped by the passenger, and must be securely retained against inadvertent movement. In the case of a manually operated recline apparatus this may be achieved by means of a system of spring-loaded teeth and slots similar to a manual car seat adjuster. If the recline motion is to be operated using a motor and reduction gear system, the force required to back drive the unpowered motor is normally sufficient to prevent movement of the carriage. Except for TTL (taxi, takeoff or landing) the loads that might cause the carriage to move are in the order of 1.5 G-2 G in a forward or aft direction. For TTL the loads that must be sustained are 9 G (static) or 16 G (dynamic) in the forward direction and 1.5 G in the aft direction.
It is desirable therefore to provide an apparatus for locking a vehicle seat with respect to its slide mechanism, and in particular for locking a seat's movable recline carriage with respect to a fixed lower structure, especially in the event of an accident.